DOC-634: 1st pass at client protocol doc conversion and import [v/5.6] (#1951)

Backport of #1947

Converts internal .md template into .adoc and manually removes version
history and copyright notice (changes should be made in source doc for
future). No copy review.

Co-authored-by: Oliver Howell <[email protected]>

Author: devOpsHazelcast

docs/modules/ROOT/nav.adoc

@@ -514,6 +514,7 @@
 
 .Clients and APIs
 * xref:clients:client-overview.adoc[Overview]
+** xref:clients:client-protocol.adoc[]
 * Clients
 ** xref:clients:java.adoc[]
 ** xref:clients:dotnet.adoc[]

docs/modules/clients/pages/client-overview.adoc

@@ -12,13 +12,15 @@ see the link:https://hazelcast.com/developers/clients/?utm_source=docs-website[c
 
 Hazelcast provides clients and programming language APIs to interact with Hazelcast clusters and leverage their distributed computing capabilities. The choice between using a client or an API depends on your specific use case, performance requirements, and the programming languages you're using in your project. The following examines the key differences and considerations.
 
-NOTE: *Clients* refer to the Hazelcast _libraries_ used to connect to a Hazelcast cluster and exchange data. Clients use a binary protocol for communication with the cluster and encode the data in various formats such as Compact, JSON, etc. Clients are available in various programming languages. 
+NOTE: *Clients* refer to the Hazelcast _libraries_ used to connect to a Hazelcast cluster and exchange data. Clients use a xref:clients:client-protocol.adoc[binary protocol] for communication with the cluster and encode the data in various formats such as Compact, JSON, etc. Clients are available in various programming languages. 
 *APIs*, by comparison, are the _interfaces_ with the Hazelcast platform. These do not require the use of specific libraries to connect and are generally text based — for example, the REST interface.
 
 === Clients
 
 Hazelcast clients must be installed locally to communicate with the server.
 
+NOTE: For detailed information on the client protocol used, see xref:clients:client-protocol.adoc[].
+
 ==== Benefits of using Hazelcast clients
 
 * Language flexibility: Hazelcast offers clients in multiple programming languages, allowing you to use Hazelcast in various environments. 
@@ -86,4 +88,5 @@ For detailed information and code samples for each client, see:
 For help getting started with the Hazelcast clients, see the client tutorials in xref:clients:hazelcast-clients.adoc[Get started with a Hazelcast Client].
 
 For details about using Memcache to communicate directly with a Hazelcast cluster, see xref:memcache.adoc[Memcache].
+
 For information about using the REST API for simple operations, see: xref:rest.adoc[REST].